skip to main content

Title: STATISTICAL ANALYSIS OF THE HEAVY NEUTRAL ATOMS MEASURED BY IBEX

We investigate the directional distribution of heavy neutral atoms in the heliosphere by using heavy neutral maps generated with the IBEX-Lo instrument over three years from 2009 to 2011. The interstellar neutral (ISN) O and Ne gas flow was found in the first-year heavy neutral map at 601 keV and its flow direction and temperature were studied. However, due to the low counting statistics, researchers have not treated the full sky maps in detail. The main goal of this study is to evaluate the statistical significance of each pixel in the heavy neutral maps to get a better understanding of the directional distribution of heavy neutral atoms in the heliosphere. Here, we examine three statistical analysis methods: the signal-to-noise filter, the confidence limit method, and the cluster analysis method. These methods allow us to exclude background from areas where the heavy neutral signal is statistically significant. These methods also allow the consistent detection of heavy neutral atom structures. The main emission feature expands toward lower longitude and higher latitude from the observational peak of the ISN O and Ne gas flow. We call this emission the extended tail. It may be an imprint of the secondary oxygen atoms generated bymore » charge exchange between ISN hydrogen atoms and oxygen ions in the outer heliosheath.« less
Authors:
; ;  [1] ;  [2] ; ; ;  [3]
  1. Space Science Center and Department of Physics, University of New Hampshire, 8 College Road, Durham, NH 03824 (United States)
  2. Pysics Institute, University of Bern, Bern 3012 (Switzerland)
  3. Southwest Research Institute, P.O. Drawer 28510, San Antonio, TX 78228 (United States)
Publication Date:
OSTI Identifier:
22520101
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal, Supplement Series; Journal Volume: 220; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; 79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ATOMS; CHARGE EXCHANGE; COSMIC GASES; GAS FLOW; HELIOSPHERE; HYDROGEN; INTERSTELLAR SPACE; KEV RANGE; NITROGEN; NOISE; OXYGEN; OXYGEN IONS